Bizarre: Sendmail Connects Then Times Out...Sendmail Gurus Please Help

Bizarre: Sendmail Connects Then Times Out...Sendmail Gurus Please Help

Post by Will Est » Sat, 14 Sep 1996 04:00:00



I am having a bizarre problem with a Sun mail host running Sendmail
8.6 that times out after connecting to another host.  I need help
deducing the cause of the problem.

Let's call the sendmail host A.  The destination host is running an NT
SMTP MTA.  Let's call the destination host B.

When A sends to B inside the corporate network, A connects then times
out.  The logs on both A and B show a connection is made, but the
connection times out shortly after the 220 introduction message from
host B, or during the SMTP HELO.  However, when I telnet from host A
to host B's SMTP port, I am able to do an SMTP transaction manually.
This suggests that the IP connection works fine between these
machines.  In addition, I can send mail directly to host B from many
other hosts with no problem.

Here is where it gets bizarre.  If I take host B and put it on the
Internet, host A can send to it without any problem (it has a
different IP and DNS name on the Internet, of course).  This tends to
rule out a problem with the SMTP MTA on the host B side.

So, IP seems to work okay.
Host B receives mail from other hosts.
Host B receives mail from host A as long as host B is on the Internet.
Host A times out during the connect to Host B when sending mail to
host B on the internal network.

This one has me stumped.  It is almost like IP packets are getting
through to host B but not routing back correctly.  I don't see how
that would be possible, though, because I can make the connection
manually.

Any hints are appreciated.

--
Will Estes                                  U.S. Computer

                                            Saratoga, CA  95070
                                            FAX: 408-446-1013

 
 
 

Bizarre: Sendmail Connects Then Times Out...Sendmail Gurus Please Help

Post by Per Hedela » Sun, 15 Sep 1996 04:00:00



>I am having a bizarre problem with a Sun mail host running Sendmail
>8.6 that times out after connecting to another host.  I need help
>deducing the cause of the problem.

Your problem is that the Sun-supplied sendmail.cf, which you apparently
use, only specifies the line termination E=\r\n (i.e. <CR><LF>) for the
"ddn" mailer, not the "ether" mailer. Sun's old version of sendmail (for
which their .cf was produced) used <CR><LF> by default, but version 8
(before 8.8) does not (default is bare <LF>).

Recieving sendmails don't care whether you use <CR><LF> or <LF>, but
some other MTAs do, among them the NT one you're running, it seems - and
they can't be faulted for that, as RFC821 specifies that <CR><LF> should
be used. Finally, if you're using this sendmail.cf the way Sun intended
it, the "ether" mailer will be used for mail within your domain (or
something like that), and the "ddn" mailer for external mail.

I.e. the fix is to add ", E=\r\n" to the end of the "Mether" line. Of
course Sun should have done this (actually they have in Solaris 2.5.1,
probably also in patches to earlier versions), or better still shipped
the v8 m4 package, which of course has E=\r\n in all the needed places,
with their "v8" sendmail.

--Per Hedeland